The invention relates to a differential gear unit for motor vehicles for controllably distributing the driving force between two output shafts, composed of a housing and therein a differential gear with an input element and two output elements which have a drive connection to the output shafts, a step-up gear unit (or step-down gear unit) which has a drive connection on the drive side to the input element of the differential gear, and two adjacent, hydraulically activated controllable clutches which have a drive connection on one side to the output side of the step-down gear unit and on the other side, to one output shaft each, so that an additional torque can be imparted to the output shafts depending on the position of the friction clutches, said clutches here each having an inner part, an outer part, a laminated disk pack and a pressing-on piston.
Such differential gear units can be used both as an intermediate axle differential of an all-wheel-driven motor vehicle for distributing the driving force to the front axle and the rear axle, and also as an axle differential for distributing the driving force between the wheels of one axle. In the first case, the two output shafts have a drive connection to the axles, and in the second case they have a drive connection to the individual wheels of the axle.
EP 662 402 B1, whose subject matter is an axle differential, discloses arranging both friction clutches on the same side of the differential gear. In this arrangement, the step-up gear unit has a drive connection on the output side to the outer part which is common to the two friction clutches. However, this requires the pressure medium to be supplied separately to permit the friction clutches to be activated independently of one another by means of two rotary input elements and an unsatisfactory arrangement of the activation elements. Furthermore, in each case the inner parts of the two friction clutches are connected to an output shaft. This arrangement is difficult to mount and also difficult to access for maintenance and repair given a correspondingly divided housing.
The object of the invention is to remedy these deficiencies and to propose an arrangement which avoids the notorious rotary input elements, and which is easy to mount and access.